Efficient and effective immobilization of tetracycline and copper from wastewater by zero-valent iron fabricated hydrochar derived from walnut peel

Abstract

Antibiotics and heavy metals often coexist as non-point-source contaminants in wastewater and their quite contrary physiochemical properties make their co-removal processes challenging. In this work, a bifunctional zero-valent iron-modified hydrochar derived from walnut peel (MWPHC) was synthesized, which was then applied for the simultaneous removal of tetracycline (TC) and Cu(II) from wastewater. Based on the characterizations, Fe0 species were successfully distributed on the surface of the walnut peel substrates. The TC and Cu(II) could be synergistically immobilized, and bridging effects were observed between them, and MWPHC exhibited excellent ability on the simultaneous removal of TC (qmax = 433.59 mg/g) and Cu(II) (qmax = 586.25 mg/g). Furthermore, the engineering feasibility of the MWPHC was evaluated using column and regeneration experiments. These results shed light on the tailored MWPHC as an environmental functional material for pollution control of co-existing antibiotic and heavy metal contaminants in agro-industrial wastewater.